Sinus tarsi is a syndrome specific to the sinus tarsi, also known as the eye of the foot, which is an opening outside the foot between the ankle and heel bone.

This syndrome was first described by Dr. Denis O'Connor in 1957. He created a surgical procedure, called the O'Connor procedure, that involves the removal of all or portions of the contents of the sinus tarsi.

Sinus tarsi syndrome can be caused by an inversion (rolling out) ankle sprain or a pinching or impingement of the soft tissues of the sinus tarsi due to an extremely pronated foot.

Patients typically complain of localized pain in the sinus tarsi region with a sense of instability and aggravation by weight bearing activity. These patients usually have a difficult time walking on grass, gravel, etc. A physical examination shows pain to palpation of the sinus tarsi with pain increasing on turning in or turning out. The foot and ankle joints may also be loose or instability.

Your podiatrist will examine the foot and order X-rays, a bone scan, CT scan, and/or MRI evaluation. However, this can be a difficult diagnosis to make, as other conditions and syndromes are often ruled out first.

Your podiatrist may recommend anti-inflammatories, stable shoes, periods of immobilization, ankle sleeves, and orthotics for decreasing the pain. Cases that are proving resistant to non-invasive treatment may require oral steroids, steroid injections, and physical therapy. Surgery is rarely necessary, but if unavoidable, open surgery through an incision or closed surgery via arthroscopy may be considered.

Sinus tarsi syndrome commonly happens after an ankle sprain or in someone who has a severely pronated foot. It is important to get a correct diagnosis so the root problem can be addressed